Subsonic cartridge for gas-operated automatic and semiautomatic weapons

ABSTRACT

A subsonic cartridge that enables a conventional automatic or semiautomatic weapon to fire a projectile at a subsonic velocity and cycle the weapon to eject the spent cartridge case, without the sonic report characteristic of supersonic projectile velocities. The cartridge includes a case having a tubular shape with an open end oppositely disposed head, and a bore therebetween. The head of the case includes a primer cavity, a web separating the primer cavity from the bore, and a flash hole through the web. A primer is stored within the primer cavity, and projectile is disposed within the bore so as to close the open end of the cartridge case. A charge cavity is delimited within the bore between the web and the projectile. The charge cavity is sized and shaped to contain a limited amount of propellant charge that propels the projectile from the cartridge case at a subsonic speed.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation-in-part patent application of co-pending U.S. patent application Ser. No. 09/416,448 which is a continuation-in-part patent application of copending U.S. patent application Ser. No. 08/788,216 filed Jan. 27, 1997, abandoned.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention generally relates to firearm cartridges, including those for use in automatic and semiautomatic weapons. More particularly, this invention relates to a cartridge for propelling a projectile at subsonic velocities and which is capable of cycling the reciprocating bolt of a gas-operated automatic and semiautomatic weapon.

[0004] 2. Description of the Prior Art

[0005] Many automatic and semiautomatic weapons are gas-operated, in that they use cartridge ammunition with a propellant charge that is not only adequate to expel the projectile (bullet) from the cartridge case and weapon, but must also develop sufficient chamber pressure to cycle the reciprocating bolt of the weapon, during which the spent case is ejected and the next cartridge is loaded. There are various types of cartridges for projectiles used in gas-operated automatic and semiautomatic weapons. For example, different cartridge cases are available for .223 caliber (5.56 mm) bullets fired from the United States Model Colt M-4 and M-16/AR-15 weapons. These weapons fire .223 caliber projectiles at velocities of approximately 3000 feet/second (about 900 m/s), i.e., far exceeding the speed of sound (about 330 m/s, or about 1100 feet/second). It is believed that a cartridge is not available for use with conventional gas-operated automatic or semiautomatic weapons, which can cycle the weapon to eject a spent cartridge case yet also propel the projectile at a subsonic velocity to reduce the level of sound at firing, i.e., to avoid the sonic report produced as a result of the projectile exceeding the speed of sound. More particularly, a cartridge is not available that can fire a projectile at a subsonic speed and simultaneously develop sufficient chamber pressure to cycle the reciprocating bolt of a gas-operated weapon. As an example, a subsonic cartridge is not available that can develop a chamber pressure of at least 45,000 psi (about 3100 bar), which is generally required to cycle the Colt M-4 weapon when firing a .223 caliber cartridge.

[0006] The use of a sound suppressor, silencer or sound moderator to reduce the sound produced by a weapon is well known, an example being the integrated sound suppression available for gas-operated automatic and semiautomatic weapons such as the M-4 and M-16/AR-15 weapons. While being effective to considerably reduce the sound level produced when fired, conventional sound suppression devices cannot suppress the loud report of a supersonic projectile. Because of the present requirement to use supersonic cartridges to produce chamber pressures sufficient to cycle their reciprocating bolts, gas-operated automatic and semiautomatic weapons produce a sonic report even though equipped with sound suppression. U.S. Pat. No. 5,033,356 to Richardson discloses a firearm noise suppressor that reduces the velocity of a projectile fired using a cartridge. Richardson explains that in most situations, the noise suppressor reduces the projectile velocity to subsonic speeds. However, Richardson uses conventional ammunition, and then modifies the firearm barrel to include an external chamber into which gases are vented as the projectile travels though the bore past a port that vents the bore to the chamber. One example presented by Richardson involves firing a conventional supersonic round at a subsonic velocity. However, in the example an AR-15 9-mm weapon is used, which is not gas-operated.

[0007] In view of the above, it can be appreciated that there is a need for a cartridge that is capable of cycling a reciprocating bolt of a gas-operated automatic or semiautomatic weapon, as well as capable of propelling a projectile from such a weapon at a subsonic velocity, so that the weapon produces minimal sound when fired.

SUMMARY OF THE INVENTION

[0008] According to the present invention, there is provided a subsonic cartridge that enables a conventional gas-operated automatic or semiautomatic weapon to fire a projectile at a subsonic velocity and cycle the weapon to eject a spent cartridge case, without the sonic report characteristic of supersonic projectile velocities. The present invention is suitable for use with gas-operated weapons having attached or integral sound suppressors, silencers or sound moderators, to provide the capability of even further sound reduction.

[0009] According to the present invention, the subsonic cartridge includes a cartridge case having a tubular shape with an open end, an oppositely disposed head, and a bore therebetween. the head of the case includes a primer cavity, a web separating the primer cavity from the bore and a flash hole through the web. A primer is stored within the primer cavity, and a projectile is secured within the open end of the cartridge case. A charge cavity is delimited within the bore between the web and the projectile. According to this invention, the charge cavity has a noncylindrical shape; having a reduced capacity than if the diameter of the charge cavity was constant and the same as that of the projectile. In a preferred embodiment, the charge cavity is tapered so that the cross-sectional area of the charge cavity adjacent the projectile is greater, preferably at least 50% greater, than the cross-sectional area of the charge cavity adjacent the web. Finally, a propellant charge is contained within the charge cavity in an amount sufficient to propel the projectile from the cartridge case at a subsonic speed.

[0010] According to the above, the present invention provides a cartridge with a charge cavity that is sized and shaped to contain an amount of propellant charge that will propel a sufficiently heavy projectile at a subsonic velocity. As used herein, a “sufficiently heavy” projectile is heavier than projectiles conventionally used with a given cartridge, and preferably formed of a material that is more dense that lead. The shape of the charge cavity limits the amount of propellant charge that can be contained in the cartridge case. In the preferred embodiment, the tapered shape of the charge cavity positions relatively less propellant charge immediately adjacent the primer, which is believed to reduce temperature velocity variations during combustion of the propellant charge. According to the invention, the amount of the propellant charge is also sufficient to cycle a gas-operated reciprocating bolt of an automatic or semiautomatic weapon if a sufficiently heavy projectile is used. Accordingly, the cartridge of the present invention enables a subsonic round to be fired from a gas-operated automatic or semi-automatic weapon, without requiring any modifications to the weapon. Such a weapon can be equipped with a sound suppression device in order to further reduce the level of sound produced when a subsonic round of this invention is fired.

[0011] Other objects and advantages of this invention will be better appreciated from the following detailed description.

BRIEF DECRIPTION OF THE DRAWINGS

[0012] The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0013]FIG. 1 is a cross-sectional view of a cartridge configured in accordance with a preferred embodiment of the present invention;

[0014]FIG. 2 is an exploded view of the cartridge of FIG. 1; and

[0015]FIG. 3 is a sectional view of a Model Colt M-16/AR-15 automatic weapon in which cartridges in accordance with FIGS. 1 and 2 are loaded.

[0016]FIG. 4 is a cross-sectional view of a preferred projectile of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] A preferred embodiment of a cartridge 10 of this invention is shown in FIGS. 1 through 3. The cartridge 10 depicted is a .223 caliber (5.56 mm), though the teachings of this invention can be applied to calibers of .22 to .50 if appropriate adjustments are made for propellant charge and projectile weight, as explained below. As is generally conventional, the cartridge 10 is composed of a case 12 that may be formed of brass, such as casings manufactured by Olin Winchester. The case 12 has a generally tubular shape with an internal bore 14, an open end 16 and an oppositely disposed head 18. The case 12 is shown as having a flange or crimp 20 at an angle of about 23 degrees from the longitudinal axis of the case 12, though it is foreseeable that crimps at different angles could be used. The case 12 has an overall length of about 1.76 inches (about 44.7 mm), and outer diameters of about 0.378 inch (about 9.60 mm) at the head 18, about 0.354 inch (about 8.99 mm) adjacent the crimp 20, and about 0.253 inch (about 6.43 mm) at the open end 16. The length of the case 12 from the head 18 to the crimp 20 is about 1.438 inches (about 36.53 mm). The internal diameter of the open end 16 is about 0.224 inch (about 5.69 mm). Those skilled in art will appreciate that the above dimensions are by example for a .223 caliber cartridge, and that the dimensions of the case 12 can differ, particularly for different calibers.

[0018] As is generally conventional, the head 18 includes a primer cavity 22, a web 24 that separates the primer cavity 22 from the bore 14, and a flash hole 26 through the web 24 so that the primer cavity 22 communicates with the bore 14. The flash hole 26 is generally aligned on the longitudinal axis of the bore 14. The primer cavity 22 contains a boxed primer 28, such as any one of those commercially available from Olin Winchester, C.C.I., Remington Arms Co. and others. The boxed primer 28 is preferably classified as a C.C.I. 41 military sensitivity primer.

[0019] A projectile 30 is secured within that portion of the bore 14 at the open end 16. The projectile 30 has a diameter of about 0.223 inch (about 5.66 mm), corresponding to the caliber of the cartridge 10. The projectile 30 can be formed of various materials. However, it has been unexpectedly found that, in order to cycle a gas-operated weapon in accordance with this invention, the projectile must be heavier than conventionally used for the particular caliber of the cartridge 10. For example, a conventional .223 cartridge employs a projectile weighing about 40 to 80 grains (about 2.6 to 5.2 g), typically about 55 grains (about 3.6 grams) for a conventional .223 caliber Remington round and about 62 grains (about 4.0 g) for military cartridges. In contrast, projectiles 30 for the cartridge 10 of this invention preferably weigh at least 100 grains (about 6.5 grams), more preferably about 130 grains to about 185 grains (about 8.4 grams to about 12.0 grams) for the .223 caliber cartridge 10 shown in FIGS. 1 and 2. For other calibers it is believed that suitable projectiles are preferably at least 25% heavier, more preferably at least 50% heavier, than the maximum projectile weight for a conventional cartridge commercially available for the caliber. Otherwise, it is believed that the cartridge 10 would not properly cycle a gas-operated weapon.

[0020] In view of the above, the projectile must either be physically larger or formed of a relatively denser material than conventionally used, i.e., specific gravities greater than 11.7 for lead. Suitable materials for the projectile 30 include high-density lead alloy cores having a coated copper jacket exterior, such as those manufactured by Allred Bullet Co., Serria Bullets, etc. More preferred materials for the projectile 30 include high-impact high-density frangible tungsten composite projectiles, such as those manufactured by AccuTec USA. In a preferred embodiment, the overall length of the cartridge 10 (case 12 with projectile 30) is about 2.223 inches (about 5.646 cm). Those skilled in the art will appreciate that if the projectile is formed of lead, the length of the projectile 30 must be increased to achieve the weight required by this invention, and that the weapon from which the projectile 30 is fired may require a particular barrel twist and/or barrel length to stabilize the projectile. For example, an M-4 may require a barrel length of about 14.5 inches (about 36.8 cm) and a 1-in-7″ rifle twist to stabilize a projectile formed from lead.

[0021] Contained within the bore 14 between the web 24 and projectile 30 is a propellant charge 32, such as gun powder composition commercially available under the name Hodgdon 870 from Hodgdon Powder Company, Inc. Other suitable gun powders are commercially available from Dupont, Accurate Powder, Hercules and Vihta Vuori. According to this invention, the amount of propellant charge 32 contained within the bore 14 is less than that conventionally used in order to propel the unconventionally heavy projectile 30 of this invention at a subsonic velocity. More preferably, the case 12 contains a sufficient amount of the propellant charge 32 to expel the projectile 30 from the barrel of a weapon at a subsonic velocity of about 1050 feet/second (about 320 m/s). A preferred amount of propellant charge 32 for the .223 caliber cartridge 10 of FIGS. 1 and 2 is 14.0 grains (about 0.907 g) or less. The amount of propellant charge 32 required to achieve subsonic performance will inherently vary with projectile weight. For example, the amount of charge 32 is increased/decreased with an increasing/decreasing mass, respectively, for the projectile 30. In an M-4 .223 caliber weapon having a gas-operated reciprocating bolt and a barrel length of about ten to twenty inches (about twenty-five to fifty centimeters), the propellant charge 32 must be sufficient to produce a chamber pressure of at least 45,000 psi (about 3100 bar), preferably about 45,000 psi to 51,000 psi (about 3500 bar). Those skilled in the art will appreciate that the required chamber pressure will depend in part on the caliber and barrel length of the weapon from which the projectile 30 is fired.

[0022] A key aspect of the present invention is that the bore 14 of the case 12 is shaped to properly contain and position the propellant charge 32 within the case 12 to facilitate uniform powder burn, resulting in positive powder ignition, uniform pressures and uniform velocities. That portion of the bore 14 containing the propellant charge 32 will be referred to as the charge cavity 34. As shown, the charge cavity 34 is delimited within the bore 14 by the web 24 and projectile 30, and has a uniformly and continuously tapered shape. The volume of the charge cavity 34 is critical, in that it is sized to accommodate not more than enough propellant charge 32 to maintain subsonic velocity and function, e.g., 14 grains of propellant charge 32 for the .223 of FIGS. 1 and 2. Based on the uniform taper shown, the charge cavity 34 has a cross-sectional area adjacent the projectile 30 that is at least 50% greater than its cross-sectional area adjacent the web 24. When completely filled with the propellant charge 32, the uniformly tapered shape of the charge cavity 34 improves reliability, powder burn, and temperature/velocity variations. However, the charge cavity 34 could have a noncylindrical shape other that that shown in the Figures and still achieve the object of this invention.

[0023] The cartridge 10 of this invention is intended for loading in conventional gas-operated automatic or semiautomatic weapons, such as the Colt M-16/AR-15 weapon 36 depicted in FIG. 3. The .223 caliber cartridge 10 of FIGS. 1 and 2 can also be adapted to operate in other M-16 rifles having barrel lengths of about ten to twenty inches, as noted above. The weapon 36 is shown in FIG. 3 without an attached or integral sound suppressor, silencer or sound moderator, though it is within the scope of this invention that the weapon 36 could be so equipped as well known in the art. An example of a suitable sound suppressor is a silencer disclosed in U.S. Pat. No. 5,164,535 to LeaSure.

[0024] As depicted in FIG. 3, several cartridges 10 are loaded into a magazine 40 assembled to the weapon 36, whose firing sequence is well known to those skilled in the art. When the trigger of the weapon 36 is pulled, the propellant charge 32 is ignited by the primer 28, producing gases 42 that rapidly expand to dislodge the projectile 30 from the case 12 and propel the projectile 30 down the barrel 44 of the weapon 36. In the gas-operated weapon 36, the expanding gases 42 also fill a cavity 46 within a bolt carrier 48 of the weapon 36, by which the bolt carrier 48 is cycled to eject the spent case 12 and load the next cartridge 10 from the magazine 40. The expanding gases 42 enter the cavity 46 by traveling from the spent case 12 down the barrel 44 into a gas port 50 of a gas tube assembly located under the front sight assembly 52 of the weapon 36, as depicted in FIG. 3. As noted above, the expanding gases 42 preferably create a chamber pressure of about 45,000 psi to about 51,000 psi, depending on the length of the barrel 44. As the expanding gases 42 fill the cavity 46, the bolt carrier 48 is cycled rearward, causing an extraction and ejection cycle such that the case 12 from the discharged cartridge 10 is ejected from the weapon 36. Extraction of the next cartridge 10 from the magazine 40 occurs as the reciprocating bolt 54 and bolt carrier 48 are in a forward cycle, during which the bolt 54 strips the next cartridge 10 from the magazine 40 into the barrel chamber 56 if the weapon 36, which is then ready for firing.

[0025] In an initial investigation, cartridges similar in outward appearance to that shown in FIG. 1 were evaluated. The cartridges had a heavy projectile (100 grains, about 6.5 g) and a reduced propellant charge, but a conventional case. The cartridges were fired from an M-16 weapon having a barrel length of about 14.5 inches (about 36.8 cm), with ballistic data gathered with the assistance of Barnes Bullets, Inc. The weapon was fired with and without an attached suppressor. When fired, the cartridges cycled the weapon without producing a load sonic report, i.e., did not exceed the speed of sound. The chamber pressure measured during firing of the cartridges was about 51,000 psi (about 3500 bar), and muzzle velocities of the projectiles were about 1050 ft/sec (about 320 m/s). Projectile velocities were about 984 ft/sec (about 300 m/s) after traveling about 150 meters, suggesting an effective range of over 200 meters. When the cartridges were fired from the weapon with an attached sound suppressor, almost no sound was produced. From these tests, it was concluded that a cartridge with a heavier projectile and reduced propellant charge could achieve subsonic projectile velocities when fired from a gas-operated automatic or semiautomatic weapon having a length of about ten to twenty inches (about 25 to 50 cm).

[0026] In a subsequent investigation leading to this invention, .223 caliber cartridges configured in accordance with FIGS. 1 and 2 underwent ballistic testing using a gas-operated Colt M-4 carbine having a barrel length of about 14.5 inches (about 36.8 cm) and with and without a silencer. The test showed that the cartridge of this invention was able to propel 145 grain, .223 projectiles at subsonic velocities and properly cycle the weapon. Chamber pressures of about 48,000 psi (about 330 bar) were measured for exit velocities of about 1040 ft/s (about 317 m/s), with a velocity of about 1000 ft/s (about 305 m/s) being measured after the projectiles had traveled about 300 feet (about 90 m). From these tests, it was concluded that .223 caliber projectiles fired from the tested weapon would have an effective range of at least 250 yards (about 230 m).

[0027] From the above tests, it was further concluded that the invention is particularly advantageous for .308 caliber (7.62 mm) cartridges. For this caliber, a suitable projectile and propellant charge combination is believed to be about 180 to about 300 grains (about 11.7 to about 19.4 g) for the projectile 30 and about 14 to 18 grains (about 0.91 to about 1.2 g) for the propellant charge 32. As previously noted, different calibers can benefit from this invention, as long as the projectile and propellant charge are appropriately increased and decreased together to maintain the desired subsonic performance.

[0028] A preferred projectile is illustrated, in cross-sectional view, in FIG. 4. In FIG. 4, the projectile 30 comprises a nose 60 and tail 61. The nose 60 is preferably tapered relative to the body 62. The tail 61 is also preferably tapered. A tapered nose and tail enhance the ballistic performance of a projectile as known in the art. At least one recess 64 in the projectile is provided thereby forming at least one ring 63 around the projectile. The ring 63 and body 62 are preferably the same diameter. The recess preferably has a depth of about 0.003 -0.010 inch, more preferably 0.003-0.006 inch. In a particularly preferred embodiment three recesses are provided thereby forming three distinct rings. It is most preferred that the rearmost ring be wider than the interior rings. The ring width is preferably at least about 0.05 inches to 0.13 inches. In a particularly preferred embodiment the rearward most ring has a width of approximately 0.12 inches with two interior rings each having a width of approximately 0.05 inches. The width of each recess is preferably approximately 0.07 inches. The projectile is preferably at least 114 grains to no more than approximately 135 grains. A particularly preferred embodiment comprises an approximately 123 grain projectile with an overall length of approximately 1.100 and thickness of approximately 0.224 inches. The preferred tail is approximately 0.2 inches in length with a diameter of approximately 0.204 inches towards the front of the projectile and a diameter of approximately 0.15 inches at the end. A series of rings and recesses, with the first ring being approximately 0.120 inches wide, and the second and third rings being approximately 0.05 inches wide is most preferred. The three recesses preferably have a width of approximately 0.070 inches each. The body is approximately 0.47 inches long, as measured from the forward end of the forward most recess with a taper comprising a radius of approximately 0.330 inches terminating at a blunt edge approximately 0.125 inches in diameter.

[0029] While not limited to any theory the alternating recesses and rings are postulated to trap subsonic gases thereby optimizing pressure by minimizing pressure losses.

[0030] While the invention has been described in terms of a preferred embodiment, it is apparent that other forms could be adopted by one skilled in the art. In addition to different calibers, cartridges within the scope of this investigation can have configurations that differ that shown in the Figures, and appropriate materials could be substituted for those noted. Accordingly, the scope of the invention is to be limited only by the following claims. 

What is claimed is:
 1. A cartridge loaded in a gas-operated weapon selected from the group consisting of gas operated automatic and semiautomatic weapons, the cartridge comprising: a cartridge case having a tubular shape with an open end, and oppositely disposed head, and a bore therebetween, the head having a primer cavity, a web separating the primer cavity from the bore, and a flash hole through the web; a primer stored within said primer cavity; a projectile disposed within the bore so as to close the open end of the cartridge case, the projectile having a weight of about 100 grains or more; a charge cavity delimited within the bore between the web and the projectile; and a propellant charge contained within the charge cavity in an amount sufficient to propel the projectile from the cartridge case at a subsonic speed and to recycle the weapon.
 2. A cartridge according to claim 1, wherein the cartridge is a .223 caliber, and the charge cavity is sized to accommodate about 14 grains of the propellant charge.
 3. A cartridge according to claim 1, wherein the projectile has a weight of up to about 130 grains.
 4. A cartridge according to claim 1, wherein the propellant charge completely fills the charge cavity.
 5. A cartridge according to claim 1, wherein the cartridge is a .308 caliber, the projectile weighs about 180 to about 300 grains, and the charge cavity is sized to accommodate about 14 to about 18 grains of the propellant charge.
 6. A cartridge according to claim 5, wherein the propellant charge completely fills the charge cavity.
 7. A cartridge according to claim 1, wherein the projectile has a specific gravity of greater than 11.7.
 8. A cartridge according to claim 1, wherein the projectile has a caliber of from .22 to .50.
 9. A cartridge according to claim 1, wherein the weapon has a barrel length of about 10 to about 16 inches.
 10. A cartridge according to claim 1, wherein said projectile comprises at least one recess circumventing said projectile.
 11. A cartridge according to claim 10 wherein said projectile comprises at least one ring adjacent to said recess.
 12. A cartridge according to claim 11 wherein said projectile comprises three recesses and three rings.
 13. A cartridge according to claim 11 wherein said ring is at least approximately 0.05 inches to no more than approximately 0.13 inches in width.
 14. A cartridge according to claim 11 wherein said recess has a depth of at least approximately 0.003 inches to no more than approximately 0.010 inches.
 15. A cartridge according to claim 14 wherein said depth is no more than approximately 0.006 inches.
 16. A cartridge according to claim 12 wherein said projectile is at least approximately 114 grains to no more than approximately 135 grains.
 17. A cartridge according to claim 16 wherein said projectile is approximately 123 grains.
 18. A .223 caliber cartridge loaded in a recycling weapon having a gas-operated reciprocating bolt, the cartridge comprising: a cartridge case having a tubular shape with an open end, an oppositely disposed head, and a bore therebetween, the head having a primer cavity, a web separating the primer cavity from the bore, and a flash hole through the web; a primer stored within the primer cavity; a projectile disposed within the bore so as to close the open end of the cartridge case, the projectile having a weight of about 130 grains; a charge cavity delimited within the bore between the web and the projectile; and about 14 grains of propellant charge that completely fills the charge cavity, the propellant charge within the charge cavity being an amount sufficient to propel the projectile from the cartridge case at a subsonic speed and to recycle the reciprocating bolt of the weapon.
 19. A .223 caliber cartridge according to claim 18, wherein the recycling weapon is chosen from the group consisting of gas operated automatic and semiautomatic weapons.
 20. A .223 caliber cartridge according to claim 19, wherein the weapon has a barrel length of about 10 to about 16 inches, and the amount of the propellant charge in the charge cavity is sufficient to procedure a pressure of about 45,000 psi to 51,000 psi when ignited to propel the projectile from the cartridge case.
 21. A process of firing a cartridge from a gas-operated automatic or semiautomatic weapon, the process comprising the steps of: providing a cartridge comprising: a cartridge case having a tubular shape with an open end, an oppositely disposed head, and a bore therebewteen, the head having a primer cavity, a web separating the primer cavity from the bore, and a flash hole through the web; a primer stored within the primer cavity; a projectile disposed within the bore so as to close the open end of the cartridge case; a charge cavity delimited within the bore between the web and the projectile; and a propellant charge contained within the charge cavity in an amount sufficient to propel the projectile from the cartridge case at a subsonic speed; loading the cartridge in a gas-operated weapon chosen from the group consisting of automatic and semiautomatic weapons having a reciprocating bolt; and then firing the weapon by igniting the propellant charge, the propellant charge producing a chamber pressure sufficient to propel the projectile from the cartridge case at a subsonic speed and to recycle the reciprocating bolt of the weapon.
 22. A process according to claim 21, wherein the charge cavity has a noncylindrical shape.
 23. A process according to claim 21, wherein the charge cavity has a tapered shape.
 24. A process according to a claim 21, wherein the charge cavity has a uniformly and continuously tapered shape.
 25. A process according to claim 21, wherein the cartridge is a .223 caliber, the projectile weighs at least 100 grains, and the charge cavity is sized to accommodate not more than 14 grains of the propellant charge.
 26. A process according to claim 25, wherein the propellant charge completely fills the charge cavity.
 27. A process according to claim 21, wherein the cartridge is a .308 caliber, the projectile weighs about 180 to about 300 grains, and the charge cavity is sized to accommodate about 14 to about 18 grains of the propellant charge.
 28. A process according to claim 27, wherein the propellant charge completely fills the charge cavity.
 29. A process according to claim 21, wherein the projectile has a specific gravity of greater than 11.0.
 30. A process according to claim 21, wherein the projectile has a caliber of from .22 to .50.
 31. A process according to claim 21, wherein the weapon has a barrel length of about 10 to about 20 inches.
 32. A process according to claim 21, wherein the cartridge is a .223 caliber, the projectile weights at least 100 grains, and the amount of the propellant charge present in the charge cavity is sufficient to produce a pressure of about 45,000 psi to 51,000 psi when ignited to propel the projectile from the cartridge case. 